This invention relates to four way valves, and in particular, to a four way valve utilized in reverse cycle refrigeration systems. While the invention is described in particular detail with respect to such refrigeration systems, those skilled in the art will recognize the wider applicability of the inventive concepts disclosed hereinafter.
In refrigeration systems, it is common to connect a first condenser-evaporator coil, a second condenser-evaporator coil, and an appropriate expansion device to a single refrigerant compressor through a reversible valve. The first coil ordinarily is an outdoor coil for condensing the compressor refrigerant, and the second coil is an inside coil for refrigerating the space of an enclosure such as a room or other space. In heat pump applications, the function of the first and second coils can be reversed, making the indoor coil the condenser to heat the space and the outdoor coil the evaporator coil to absorb heat from the outside. Four way valves permit easy change over between the functions of the first and second coils.
A number of four way or piston slide valves are known in the art. One particular valve useful in heat pump applications is disclosed in the U.S. Pat. to Hargraves, No. 3,985,154, owned by the assignee of the present invention. The 3,985,154 patent shows a particular embodiment for a four way valve with solenoid actuation arranged so that the distance of main valve movement may be increased or decreased appreciably, without affecting operation of the means utilized to actuate the pilot valve assembly. While the valve disclosed in the 3,985,154 patent works well for its intended purposes, the internal passageways in the main valve slide body utilized in that patent require relatively close tolerance machine operations. The machine operations affect valve cost adversely. The valve disclosed hereinafter retains the beneficial benefits of the 3,985,154 patent in that it incorporates a constant pilot stroke length, regardless of the stroke of the main valve member, but eliminates the machine operations required by the valve design disclosed in that patent.
One of the objects of this invention is to provide a four way valve having simplified construction.
Another object of this invention is to provide a low cost four way valve.
Still another object of this invention is to provide a four way valve having a main slide valve assembly, the stroke distance of which is independent of the stroke length of the solenoid device used to actuate the valve.
Yet another object of this invention is to provide a variety of four way valve designs having differing stroke lengths for the main slide valve assembly, but which employ a common solenoid actuating means.
Another object of this invention is to provide a pilot operated four way control valve in which the pilot slide is loosely mounted to a solenoid actuated device.
Still another object of this invention is to provide a pilot actuated device for a four way valve in which high pressure fluid passing through the valve is used to maintain the position of the pilot slide actuating member of the valve.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.